BREWER, Maine — Lt. Dennis Tinkham, a firefighter for the Brewer Fire Department for more than a dozen years, was fired two weeks ago, Fire Chief Gary Parent confirmed.

“He was relieved of his duties and terminated,” the chief said Monday, adding that a criminal investigation involving Tinkham is under way.

“It’s a blow” to the department’s morale, said Parent, who had worked with Tinkham since the former lieutenant began in Brewer as a firefighter 14 years ago. Tinkham became a lieutenant a decade ago and also was the city’s fire inspector.

Brewer police detectives are looking into a theft from the Brewer Fireman’s Relief Association, which provides death benefits for families left behind when a firefighter dies, Brewer police Lt. Chris Martin said Tuesday, declining to identify who is being investigated.

“No official charges have been issued at this point,” he said. “It’s an active investigation.”

City Manager Steve Bost said Monday that between $5,000 and $10,000 was missing from the firemen’s account.

Bost said he fired Tinkham, who had served as treasurer of the firemen’s relief association since April 2006, on July 15.

Tinkham since has moved to Auburn, Parent said. His phone number is not listed and email messages sent Monday and Tuesday were not immediately returned for comment.

“It was very sad,” Bost said. “It’s very unpleasant to go through something like this.”